The machining accuracy of workpiece is influenced by its orientation deviation, which is caused by the fixture-workpiece error. Based on the spatial coordinate theory, the orientation deviation of workpiece is measure...The machining accuracy of workpiece is influenced by its orientation deviation, which is caused by the fixture-workpiece error. Based on the spatial coordinate theory, the orientation deviation of workpiece is measured by using an on-machine verification system, which can take into account the errors resulting from fixture manufacturing, installation and adjustment, location and clamping of workpiece. According to the least square method, the model of orientation deviation is built to determine the relationship between the theoretical and actual coordinate systems. The influence of orientation deviation on machining accuracy is quantified, and it is shown that the orientation deviation only affects the dimensional precision and position precision, rather than shape precision. In the experiment, the compensation processing of realtime errors was conducted, and the perpendicularity and inclination errors of the tetragonal part were reduced by 38.46% and 47.06%, respectively.展开更多
In the present work,transparent and anti-fogging AlPO_(4)-5 films were prepared on glass substrates using a novel developed process.The process entails a simple in-situ sol–gel followed by vapor phase transport.The i...In the present work,transparent and anti-fogging AlPO_(4)-5 films were prepared on glass substrates using a novel developed process.The process entails a simple in-situ sol–gel followed by vapor phase transport.The in-situ sol–gel process was implemented by coating the precursor sols for the synthesis of AlPO4-5 on the glass substrates successively using the spin-coating method.The films and powders scribed from the films were characterized by X-Ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscope(SEM),atomic force microscope(AFM),X-ray photoelectron spectroscopy and transmission electron microscope(TEM).The unique films were composed of oblique oriented nanoflake AlPO_(4)-5 crystals with the thickness of about 20 nm.The formation of nano-flake crystals can be ascribed to the high concentration of the precursors,resulting in the formation of a supersaturation system.The obtained films showed high antifogging performance due to the superhydrophilicity with a water contact angle of lower than 1.0°.The silicone oil contact angle was also low about 8.2°.In addition,heteroatom-substituted AlPO_(4)-5 films showing different colors can be obtained easily by simply adding transition metal ions in the phosphate acid solution during the preparation that can extend the application of the method for different coating demand.展开更多
A new approach to synthesize liquid crystalline polymer with narrow polydispersity index（PDI） was developed.Photopolymerization of 4-cyanophenyl-4＇-（6-acryloyloxyhexyloxy）benzoate（RM23） in nematic liquid crysta...A new approach to synthesize liquid crystalline polymer with narrow polydispersity index（PDI） was developed.Photopolymerization of 4-cyanophenyl-4＇-（6-acryloyloxyhexyloxy）benzoate（RM23） in nematic liquid crystals with macroscopic orientation was studied.The effects of the monomer concentration on the molecular weight and PDI of the resulting polymers were studied through gel permeation chromatography（GPC） and polarized optical microscopy.The low PDI of 1.19 and 1.22 was obtained in the reverse and normal modes,respectively.The PDI and molecular weight increased with monomer concentration.展开更多
‘Oriental Show’ is a generation of new cucumber variety, with the superi-or inbred line ‘101’ as the female parent and inbred line ‘102’ as the male par-ent. The growth vigor tends to be strong and the first fem...‘Oriental Show’ is a generation of new cucumber variety, with the superi-or inbred line ‘101’ as the female parent and inbred line ‘102’ as the male par-ent. The growth vigor tends to be strong and the first female blossom produces on the 4th or the 5th internode. Fruit is 34 cm long and 32 cm in transverse diameter. Per fruit weighs about 230 g. lt is dark green, densely covered with thorns. lt tastes crisp, containing 167.7 mg/kg Vc, and it is resistant to downy mildew, pow-dery mildew and bacterial angular leaf spot disease. lt is yielding and tolerant to low temperature and weak luminance. The yield can be as high as over 112 443.778 kg/hm^2, and ‘Oriental Show’ is suitable to be cultivated in greenhouses in early spring or solar greenhouses in north China or Henan province.展开更多
The polarization orientation effect and porosity effect on the piezoelectric properties and related parameters are studied in 2-2-type composites based on domain-engineered relaxor-ferroelectric[011]-poled single crys...The polarization orientation effect and porosity effect on the piezoelectric properties and related parameters are studied in 2-2-type composites based on domain-engineered relaxor-ferroelectric[011]-poled single crystals.The parameters,which are of great interest,are an anisotropy of the piezoelectric coefficients d_(3j)^(*),an anisotropy of the energy-harvesting figures of merit d_(3j)^(*)g_(3j)^(*) and the hydrostatic piezoelectric coefficient d_(h)^(*).An orientation of the main crystallographic axes in each polydomain single-crystal layer is described by anglesβandγ.Diagrams built for the first time show the(β,γ)regions,where a large anisotropy of d_(3j)^(*)(or d_(3j)^(*)g_(3j)^(*))is achieved,and where inequality d_(h)^(*)>1000 pC/N holds.A large local max d_(h)^(*)=1930 pC/N is achieved in a 2-2-0 PZN-0.065PT-based composite at the longitudinal piezoelectric coefficient d33*=2290 pC/N and figure of merit d*33g*33=1.02.10−9 Pa−1.The aforementioned large parameters are to be of value in piezoelectric sensing,energy harvesting and hydroacoustics.展开更多
The kinematic error model of a 6-DOF space robot is deduced, and the cost function of kinematic parameter identification is built. With the aid of the genetic algorithm （GA） that has the powerful global adaptive pro...The kinematic error model of a 6-DOF space robot is deduced, and the cost function of kinematic parameter identification is built. With the aid of the genetic algorithm （GA） that has the powerful global adaptive probabilistic search ability, 24 parameters of the robot are identified through simulation, which makes the pose （position and orientation） accuracy of the robot a great improvement. In the process of the calibration, stochastic measurement noises are considered. Lastly, generalization of the identified kinematic parameters in the whole workspace of the robot is discussed. The simulation results show that calibrating the robot with GA is very stable and not sensitive to measurement noise. Moreover, even if the robot＇s kinematic parameters are relative, GA still has strong search ability to find the optimum solution.展开更多
In this paper, we demonstrate a new optical method for tiny strain measurements based on the principle of carrier fringes of moire interferometry. A cross-line grating with frequency of 1200 lp/mm is replicated on the...In this paper, we demonstrate a new optical method for tiny strain measurements based on the principle of carrier fringes of moire interferometry. A cross-line grating with frequency of 1200 lp/mm is replicated on the specimen surface, and the strain can be deduced from the changes in carrier fringes before and after the deformation of an object. Four coherent laser beams are used to obtain the carrier fringe patterns of field U and V. Both theoretical analysis and numerical simulation indicate that the ideal accuracy of strain can be controlled within a range of ±1με. Case study of a plane extension experiment shows that the measurement accuracy of strain can be controlled within the range of ±10με. The average strain values of every row of field U and every column of field V can be obtained by using this method, and approximated strain of every pixel in the whole-field can be further acquired, and thus it is possible to measure tiny strains occurred in a micro-field. The technology in this paper can provide comprehensive information for analyzing related mechanical content in the field of MEMS.展开更多
We elaborate an error budget for the long-term accuracy of IGS（International Global Navigation Satellite System Service） polar motion estimates, concluding that it is probably about 25-30 μas（1-sigma）overall, alt...We elaborate an error budget for the long-term accuracy of IGS（International Global Navigation Satellite System Service） polar motion estimates, concluding that it is probably about 25-30 μas（1-sigma）overall, although it is not possible to quantify possible contributions（mainly annual） that might transfer directly from aliases of subdaily rotational tide errors. The leading sources are biases arising from the need to align daily, observed terrestrial frames, within which the pole coordinates are expressed and which are continuously deforming, to the secular, linear international reference frame. Such biases are largest over spans longer than about a year. Thanks to the very large number of IGS tracking stations, the formal covariance errors are much smaller,around 5 to 10 μas. Large networks also permit the systematic frame-related errors to be more effectively minimized but not eliminated. A number of periodic errors probably also influence polar motion results, mainly at annual, GPS（Global Positioning System） draconitic, and fortnightly periods, but their impact on the overall error budget is unlikely to be significant except possibly for annual tidal aliases. Nevertheless, caution should be exercised in interpreting geophysical excitations near any of the suspect periods.展开更多
基金Supported by National Natural Science Foundation of China (No.50975200)
文摘The machining accuracy of workpiece is influenced by its orientation deviation, which is caused by the fixture-workpiece error. Based on the spatial coordinate theory, the orientation deviation of workpiece is measured by using an on-machine verification system, which can take into account the errors resulting from fixture manufacturing, installation and adjustment, location and clamping of workpiece. According to the least square method, the model of orientation deviation is built to determine the relationship between the theoretical and actual coordinate systems. The influence of orientation deviation on machining accuracy is quantified, and it is shown that the orientation deviation only affects the dimensional precision and position precision, rather than shape precision. In the experiment, the compensation processing of realtime errors was conducted, and the perpendicularity and inclination errors of the tetragonal part were reduced by 38.46% and 47.06%, respectively.
基金financial support from the Key University Science Research Project of Jiangsu Province(16KJA430007)Opening Topic of Key Laboratory of Attapulgite Resources Utilization in Jiangsu Province(HPK201804)Opening Topic of National Local Joint Engineering Research Center for Deep Utilization of Mineral and Salt Resources(SF201804)。
文摘In the present work,transparent and anti-fogging AlPO_(4)-5 films were prepared on glass substrates using a novel developed process.The process entails a simple in-situ sol–gel followed by vapor phase transport.The in-situ sol–gel process was implemented by coating the precursor sols for the synthesis of AlPO4-5 on the glass substrates successively using the spin-coating method.The films and powders scribed from the films were characterized by X-Ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscope(SEM),atomic force microscope(AFM),X-ray photoelectron spectroscopy and transmission electron microscope(TEM).The unique films were composed of oblique oriented nanoflake AlPO_(4)-5 crystals with the thickness of about 20 nm.The formation of nano-flake crystals can be ascribed to the high concentration of the precursors,resulting in the formation of a supersaturation system.The obtained films showed high antifogging performance due to the superhydrophilicity with a water contact angle of lower than 1.0°.The silicone oil contact angle was also low about 8.2°.In addition,heteroatom-substituted AlPO_(4)-5 films showing different colors can be obtained easily by simply adding transition metal ions in the phosphate acid solution during the preparation that can extend the application of the method for different coating demand.
基金The authors are grateful to NSF of China(No.50703013)Independent Innovative Position of Hubei Province for financial support of this work
文摘A new approach to synthesize liquid crystalline polymer with narrow polydispersity index（PDI） was developed.Photopolymerization of 4-cyanophenyl-4＇-（6-acryloyloxyhexyloxy）benzoate（RM23） in nematic liquid crystals with macroscopic orientation was studied.The effects of the monomer concentration on the molecular weight and PDI of the resulting polymers were studied through gel permeation chromatography（GPC） and polarized optical microscopy.The low PDI of 1.19 and 1.22 was obtained in the reverse and normal modes,respectively.The PDI and molecular weight increased with monomer concentration.
基金Supported by National Modern Agricultural Technology Industry System(CARS-25-G-28)Zhengzhou Science and Technology Major Project(162PDZX188)~~
文摘‘Oriental Show’ is a generation of new cucumber variety, with the superi-or inbred line ‘101’ as the female parent and inbred line ‘102’ as the male par-ent. The growth vigor tends to be strong and the first female blossom produces on the 4th or the 5th internode. Fruit is 34 cm long and 32 cm in transverse diameter. Per fruit weighs about 230 g. lt is dark green, densely covered with thorns. lt tastes crisp, containing 167.7 mg/kg Vc, and it is resistant to downy mildew, pow-dery mildew and bacterial angular leaf spot disease. lt is yielding and tolerant to low temperature and weak luminance. The yield can be as high as over 112 443.778 kg/hm^2, and ‘Oriental Show’ is suitable to be cultivated in greenhouses in early spring or solar greenhouses in north China or Henan province.
基金supported by the Southern Federal University(research topic“Development and Materials-Science Substantiation of the Creation of Materials and Products Based on Piezoelectric Ceramics Using Additive Technologies”,stage 2022,contract No.176/22-D,July 11th,2022).
文摘The polarization orientation effect and porosity effect on the piezoelectric properties and related parameters are studied in 2-2-type composites based on domain-engineered relaxor-ferroelectric[011]-poled single crystals.The parameters,which are of great interest,are an anisotropy of the piezoelectric coefficients d_(3j)^(*),an anisotropy of the energy-harvesting figures of merit d_(3j)^(*)g_(3j)^(*) and the hydrostatic piezoelectric coefficient d_(h)^(*).An orientation of the main crystallographic axes in each polydomain single-crystal layer is described by anglesβandγ.Diagrams built for the first time show the(β,γ)regions,where a large anisotropy of d_(3j)^(*)(or d_(3j)^(*)g_(3j)^(*))is achieved,and where inequality d_(h)^(*)>1000 pC/N holds.A large local max d_(h)^(*)=1930 pC/N is achieved in a 2-2-0 PZN-0.065PT-based composite at the longitudinal piezoelectric coefficient d33*=2290 pC/N and figure of merit d*33g*33=1.02.10−9 Pa−1.The aforementioned large parameters are to be of value in piezoelectric sensing,energy harvesting and hydroacoustics.
基金supported by National Natural Science Foundation of China(No.60775049).
文摘The kinematic error model of a 6-DOF space robot is deduced, and the cost function of kinematic parameter identification is built. With the aid of the genetic algorithm （GA） that has the powerful global adaptive probabilistic search ability, 24 parameters of the robot are identified through simulation, which makes the pose （position and orientation） accuracy of the robot a great improvement. In the process of the calibration, stochastic measurement noises are considered. Lastly, generalization of the identified kinematic parameters in the whole workspace of the robot is discussed. The simulation results show that calibrating the robot with GA is very stable and not sensitive to measurement noise. Moreover, even if the robot＇s kinematic parameters are relative, GA still has strong search ability to find the optimum solution.
基金the Basal Research Funds of National Defence Science and Technology
文摘In this paper, we demonstrate a new optical method for tiny strain measurements based on the principle of carrier fringes of moire interferometry. A cross-line grating with frequency of 1200 lp/mm is replicated on the specimen surface, and the strain can be deduced from the changes in carrier fringes before and after the deformation of an object. Four coherent laser beams are used to obtain the carrier fringe patterns of field U and V. Both theoretical analysis and numerical simulation indicate that the ideal accuracy of strain can be controlled within a range of ±1με. Case study of a plane extension experiment shows that the measurement accuracy of strain can be controlled within the range of ±10με. The average strain values of every row of field U and every column of field V can be obtained by using this method, and approximated strain of every pixel in the whole-field can be further acquired, and thus it is possible to measure tiny strains occurred in a micro-field. The technology in this paper can provide comprehensive information for analyzing related mechanical content in the field of MEMS.
文摘We elaborate an error budget for the long-term accuracy of IGS（International Global Navigation Satellite System Service） polar motion estimates, concluding that it is probably about 25-30 μas（1-sigma）overall, although it is not possible to quantify possible contributions（mainly annual） that might transfer directly from aliases of subdaily rotational tide errors. The leading sources are biases arising from the need to align daily, observed terrestrial frames, within which the pole coordinates are expressed and which are continuously deforming, to the secular, linear international reference frame. Such biases are largest over spans longer than about a year. Thanks to the very large number of IGS tracking stations, the formal covariance errors are much smaller,around 5 to 10 μas. Large networks also permit the systematic frame-related errors to be more effectively minimized but not eliminated. A number of periodic errors probably also influence polar motion results, mainly at annual, GPS（Global Positioning System） draconitic, and fortnightly periods, but their impact on the overall error budget is unlikely to be significant except possibly for annual tidal aliases. Nevertheless, caution should be exercised in interpreting geophysical excitations near any of the suspect periods.
